In many environments, it is common for deposits of grime, dirt, chemical residues or other undesirable materials to accumulate on a variety of surfaces as a result of their ordinary, daily use. This problem occurs in domestic environments as well as in industrial applications. In some instances, these deposits may be merely unattractive, whereas in other situations, the deposits may impede the function of the article on which they have accumulated, or may even present a health or safety risk. Heretofore, a variety of means have been used to clean these deposits, including manual scrubbing with detergents or hard abrasive compounds. Alternatively, sandblasting and high pressure cleaning with large volumes of water, another cleaning liquid, or steam cleaning have also been used.
The known cleaning means such as those recited above, as well as other commonly available methods and apparatus, provide entirely satisfactory results in many applications. However, under certain conditions, these previously known apparatus and methods are inconvenient, inapplicable, or unsuccessful. One common example of a previously unresolved cleaning problem is the task of cleaning tile grout of the type commonly found in residential bathrooms and kitchens, in many commercial applications such as restaurants, or in hospital environments such as operating rooms.
Grout of the type used in conjunction with tile is a hard, porous ceramic material that is frequently white in color when newly applied between the tiles. It may also be tinted to a desired color in some instances. However, with the passage of time and years of use, white or tinted grout may become discolored due to deposits of dirt, grime, mildew, or other undesirable deposits that accumulate on the porous surface of the grout. These deposits cause the grout to assume a dark gray or even black coloration that is unappealing to most persons and which may disrupt the color scheme of the floor tiles. Moreover, these accumulations of grime may harbor amounts of bacteria or other substances that may present a health hazard under certain conditions. If the tile grout is located in a hospital surgical room, these accumulations can be particularly troublesome.
When used to clean tile grout, the known cleaning methods have not provided satisfactory results for a variety of reasons. As previously noted, tile grout is an extremely hard, porous, and brittle substance. Because the accumulated deposits are often retained within the porous interstices of the grout, mechanical cleaning methods such as a detergent and a scrub brush are often unable to reach the deposits to clean them with satisfactory results. Likewise, scrubbing with a steel wire brush also fails to produce satisfactory cleaning results because the grout material is harder than the steel wire, which results in the wire brush being worn away by the scrubbing action instead of the deposits or the grout material. Thus, these means have failed to give satisfactory, results in removing unwanted deposits from the grout.
Cleaning with high pressure fluids has also been attempted in the past but has given unsatisfactory results for different reasons than those noted above. Cleaning fluid sprays that have heretofore been used have been characterized by a high pressure spray having a high volumetric flow rate. Where a liquid spray is used to generate a cleaning force, the force created by the impact of the liquid upon the surface being cleaned may be represented by the following equation: ##EQU1## Wherein N equals the cleaning force in newtons, V equals the flow rate in cubic meters per second, .GAMMA. equals the specific weight of the liquid in kilograms per cubic meter and P is the pressure of the liquid in bars. As demonstrated by this equation, the cleaning force is directly proportional to the flow rate, and also to the square root of pressure. Thus, liquid spray cleaning devices have heretofore emphasized high flow rates rather than pressure to achieve a high cleaning force.
The high flow rate associated with typical pressurized liquid cleaning apparatus and methods generally renders them unacceptable for use in an indoor application, in which there is often no facility for disposing of the large quantities of liquid that are ejected by such a liquid spray. If such a cleaning spray were used to clean a tile floor, the effluent from the spray could reach several hundred gallons within a short period of time. As can readily be seen, such a volume cf effluent would be extremely difficult to contain or otherwise dispose of in a typical household or commercial application.
Another limitation associated with high flows of cleaning liquid arises from the so called "jackhammer" effect. This characteristic, which results from the use of a high volumetric flow rate of the cleaning liquid, may damage the grout or even destroy a portion of the floor surface by blowing out complete portions of the tile grout. Thus, there has been a need to circumvent the effluent discharge problems and the jackhammer effect associated with high volumetric flow rates used in conventional liquid cleaning systems.
Other problems associated with high volumetric flow rates of cleaning liquids appear when such sprays are used to clean deposits from rolls of the type used in handling web materials such as textiles and paper, as well as synthetic fibers in filament or tow form. Rolls are used in papermaking, printing, textile or fiber machinery to provide surfaces over which the paper, textile or fiber material may pass. When this occurs, any number of binders, residues, oligomers, finishes, inks, dyes or other chemical residues or deposits may accumulate on the surfaces of these rolls. Over time, a roll surface may become so covered with these materials that its function is impeded. Thus, these accumulated substances must be cleaned from the rolls periodically.
The roll cleaning task is a very challenging operation which often must be repeated frequently. In a typical production facility, some machines having rolls may need to be shut down as often as several times per day to have accumulated deposits cleaned from the rolls therein. This operation is generally accomplished by hand using sandpaper, emery cloth, brushes, steel wool or other abrasive means to clean the roll surfaces manually. Cleaning by these means is obviously a very time consuming process. Moreover, certain portions of such rolls may be difficult to reach by manual cleaning methods. Likewise, the use of high pressure cleaning methods heretofore known has not proved to be advantageous due to the high volumetric flow characteristic thereof, as discussed above. This characteristic presents the problem cf disposing of the large liquid run off that results from a high volumetric liquid spray. The high liquid flow also presents cooling problems when used with heated rolls, as the high flow may cause cooling effects that may warp the roll material, thus causing structural damage to the roll. Even if the roll is not damaged, the cooling effects may require that heated rolls, such as those that are used for drying or temperature control, be reheated prior to restarting the machinery.
In the past, cleaning of surfaces using high pressure, low volumetric flows cf liquid has been accomplished by using an intensifier pump to generate the high pressure, low volume flow cf liquid. However, the use of intensifier pumps in this application has many drawbacks which cannot be overcome due to the inherent characteristics of intensifier pumps. For example, intensifier pumps are expensive, and they are large, bulky units which cannot be transported within confined spaces. Thus, cleaning with intensifier pumps may be restricted by size constraints. As a result, if cleaning is attempted in a confined area, it may be necessary to position the intensifier pump outside the room or building and to convey the high pressure cleaning liquid to the surface to be cleaned through tubing. Because high pressure liquids at the ranges of the present invention, e.g. between 5,000 and 36,000 psi, present extreme safety hazards, they must be contained within carefully constructed and closely monitored lines to avoid the risk of injury due to unintentionally released sprays. Many industrial facilities forbid the conveyance of such high pressure liquid flows over long distances through their facilities precisely to avoid the problems caused by these lines. Moreover, even where intensifier pumps have been used in the past, multiple guards have been needed to maintain surveillance of the high pressure liquid lines that extend from the intensifier pump to the surface being cleaned to ensure that the integrity of the lines is maintained and to make certain that no accidents cause high pressure liquid to be released accidentally.
In light of the aforementioned deficiencies, it is an object of the present invention to provide a new method and apparatus that are particularly useful for cleaning hard surfaces which contain relatively hard deposits of undesirable materials of the type that are difficult to remove by conventional washing or abrading cleaning. Another object of the present invention is to provide a cleaning method and apparatus that use a high pressure liquid flow for cleaning but which avoid the difficulties associated with high volumetric flow of the cleaning liquid. It is a further object of the present invention to provide a new method and apparatus that are particularly useful for cleaning tile grout. It is a further object of the present invention to provide a new method and apparatus that are particularly useful for cleaning roll surfaces. It is a further object of the present invention to provide a new method and apparatus that are particularly useful for cleaning heated roll surfaces while avoiding excessive cooling of the rolls.